The present invention is related to transducer-protector devices for biomedical haemodialysis lines, comprising a first tubular connector of the female Luer Lock type with a conical inner surface and an outer threading, intended to be connected to a tube of a haemodialysis equipment, a second tubular connector coaxial to the first tubular connector, said first and second tubular connectors being provided with respective first and second annular radial flanges for their mutual permanent sealed connection by ultrasonic welding, and a filtering membrane made of a permeable material defining an anti-contamination sterile barrier interposed transversely between said first and second tubular connectors and having a peripheral edge clamped between said annular flanges.
These transducer-protector devices must fulfill two fundamental requirements: firstly they have to warrant in use a perfect and total hermetic tightness between the first tubular connector and the tube of the haemodialysis equipment on one side, and between the second tubular connector and the line connected to the patient on the other side. Secondly they must be capable to ensure their sterilization by means of any traditional system, namely by vapour treatment. Due to this reason the plastic material of which the first and the second radial connecting flanges are formed must be provided with characteristics such as to ensure the necessary structural and dimensional stability even in case of heating up to the vapour sterilizing temperature. Otherwise any deformations of one and/or the other radial flange might cause a non complete locking of the peripheral edge of the filtering membrane clamped between the two flanges and, as a consequence, inefficiency of the sterile barrier which such membrane must instead absolutely provide.
Due the above reason the second tubular connector with the related second annular flange is as a rule formed by one single piece of a moulded high rigidity thermoplastic material, normally polycarbonate.
On the other hand the connection between the first tubular connector of the female Luer Lock type and the tube of the haemodialysis equipment is as a rule carried out through a metallic connector of the male Luer type, joined to the tube. This connection must be perfectly hermetic, and any even slight imperfections may result in a leakage of fluid which is absolutely unacceptable. Due to this reason, use for the manufacturing of the first tubular connector together with the related first radial flange of a high rigidity thermoplastic material, for instance the same material employed for the manufacturing of the second tubular connector with the related second annular flange, which would be desirable to withstand the sterilization process of the transducer-protector device, is not envisageable.
In order to solve this problem solutions have been provided according to which the first annular flange is manufactured with the said high rigidity thermoplastic material, while the first tubular connector of the female Luer Lock type is partially or entirely manufactured with a material having higher elasticity characteristics, so as to warrant perfect hermetic tightness with the metal Luer connector of the haemodialysis equipment.
According to a first known solution, disclosed in Italian patent application No. TO93A000368 in the name of the same Applicant, the conical inner surface of the first tubular connector is formed by an insert made of a plastic material having high elasticity performance, for instance polyester or the like. Such an insert is arranged coaxially within the first tubular connector and is mechanically secured thereto.
According to a second solution, known from European Patent EP-B-0652018 also in the name of the same Applicant, the entire first tubular connector is made of said material having greater elasticity characteristics, and is provided with an axially inner attachment portion fixedly coupled by overmoulding onto a complementary outer axial attachment part of the related first radial flange.
The above known solutions, though quite efficient, have a drawback in that the method for their manufacturing is relatively complex and expensive. Actually in both cases the component elements of the transducer-protector device are three, further to the filtering membrane.